class_docstr: MRC Sample class to hold the mrc data info and provide atomic operations.
docstr: Replace the ground truth with fake answer based on specific rules
  
  :param str answer: ground truth, str
  :param list sent_tokens: sentence dicts, like [{'word': 'Saint',
      'pos': 'NNP', 'lemma': 'Saint', 'ner': 'PERSON'}...]
  :param str question: question sentence
  :return str: fake answer
docstr_tok: ["Replace","the","ground","truth","with","fake","answer","based","on","specific","rules",":","param","str","answer",":","ground","truth",",","str",":","param","list","sent_tokens",":","sentence","dicts",",","like","[","{","'word","'",":","'Saint","'",",","'pos","'",":","'NNP","'",",","'lemma","'",":","'Saint","'",",","'ner","'",":","'PERSON","'","}","...","]",":","param","str","question",":","question","sentence",":","return","str",":","fake","answer"]
code: def convert_answer(self, answer, sent_tokens, question):
      """
      Replace the ground truth with fake answer based on specific rules
  
      :param str answer: ground truth, str
      :param list sent_tokens: sentence dicts, like [{'word': 'Saint',
          'pos': 'NNP', 'lemma': 'Saint', 'ner': 'PERSON'}...]
      :param str question: question sentence
      :return str: fake answer
  
      """
      tokens = MRCCnSample.get_answer_tokens(sent_tokens, answer)
      determiner = MRCCnSample.get_determiner_for_answers(answer)
      for rule_name, func in self.get_answer_rules():
          new_ans = func(
              answer, tokens, question, determiner=determiner
          )
          if new_ans:
              return new_ans
      return None
  
imports: from .cnsample import CnSample
  from ..field import Field, CnTextField
  from ....common.utils.list_op import normalize_scope
  from ....common.preprocess.nltk_res_load import ModelManager
  from ....common.settings import *
  from nltk.stem.lancaster import LancasterStemmer
  from copy import deepcopy
label_desc: Use image node_id 20 for calling the MRCCnSample obj's underlying member method code with example usage: obj.convert_answer(answer, sent_tokens, question) and returns: None, new_ans